In the field of biological analysis and assays, small amounts of liquid must often be dispensed to predetermined locations, for example, to a plurality of wells in titer plates, capillary tubes, and/or other similar test platforms, in order to perform various analyses (e.g., testing, assays, and other procedures). Such dispensing is often automated, as it is desirable to perform numerous tests at a relatively high rate. To this end, it is also desirable to dispense a large number of small volumes of liquid simultaneously. Further, it is desirable to provide precise control over the amount of liquid dispensed, the timing of the dispensing, and/or the location of the dispensing in order to prevent wasting of materials and improve efficiency of the overall testing procedure.
Conventional devices and methods for dispensing liquids, such as liquids for biological analysis, include the use of liquid handling robots and pipettes, which often are automatically controlled to dispense a predetermined amount of liquid into each well of a titer plate. Some of these liquid handling robot devices are moved to the appropriate position corresponding to a predetermined dispensing location via motors. Conventional techniques for dividing liquid into small amounts for biological analysis include the use of capillary forces, vacuum forces, and centrifugal forces, for example. Some of these conventional liquid handling devices aspirate and/or dispense liquid to some number of wells at one time. In some cases, conventional liquid handling devices can only move liquid in or out of one well at a time. This type of device typically is able to move about three axes so as to move over any well in a two-dimensional array of wells and to move toward and away from a well. Other conventional liquid handling devices may have the ability to fill multiple wells in a plate simultaneously, for example all wells in a plate, which may permit such devices to require less axes of motion to operate and to achieve faster operating rates.
Typically, such conventional dispensing devices are configured to dispense liquid to, for example, a 96 well or 384 well titer plate configuration. To achieve faster sample testing rates (e.g., a higher throughput of sample testing), it may be desirable to increase the number of testing locations (e.g., reservoirs, wells, capillary tubes, etc.) such that more samples can be dispensed onto a testing platform simultaneously and analyzed. It may further be desirable to increase the number of reservoirs (e.g., wells) on a testing platform while keeping the platforms' overall dimensions substantially the same. In other words, it may be desirable to increase the density of the testing reservoirs on the same testing platform area, such as, for example by increasing the density of the reservoirs four-fold, eight-fold, and 16-fold. In this way, new testing platforms with a larger number of testing reservoirs could be retrofit with existing analytical systems.
In some conventional liquid dispensing devices, the size of the actuators (e.g., dispensers and/or aspirators) present a practical limit to the filling density these devices are able to achieve (e.g., the number of wells the liquid dispensing devices can fill simultaneously over a titer plate having a constant area). For example, for high-density spacing between wells (e.g., relatively small distances between adjacent wells), the actuator of conventional dispensing devices may be larger than the well spacing, thereby preventing multiple actuators from addressing adjacent wells to dispense liquid simultaneously into those wells.
Thus, it may be desirable to provide devices and methods for dispensing liquid for biological analysis that provide precise manipulation of small volumes of liquid at relatively rapid rates. Further, it may be desirable to provide relatively compact dispensing devices that can provide both liquid handling (e.g., positioning) and dispensing to a plurality of locations on a testing platform. In addition, it may be desirable to provide methods and devices that can be readily incorporated into existing biological analysis systems (e.g., workstations). For example, it may be desirable to provide a dispensing device and method that can dispense liquid to a testing platform having substantially the same dimensions as conventional testing platforms while increasing the number of locations for depositing liquid for performing testing, for example increasing the number of locations (e.g., wells) to 96, 384, 768, 1536, 3072, 6144, 12,288, 24,576, etc. In other words, it may be desirable to provide dispensing devices and methods that permit higher density dispensing of liquid, including, for example, ultra-high density dispensing applications, which may improve the overall efficiency of biological analysis systems by increasing the number of tests that can be performed at a time. In providing methods and devices that permit handling and dispensing of smaller volumes of liquid at a higher density, it may further be desirable to minimize evaporation of the liquid.
Yet further desirable features include providing dispensing devices and methods that can minimize wasted liquid during dispensing, can divide an amount of supplied liquid into precise smaller amounts, and/or deliver those precise amounts accurately to predetermined locations. It also may be desirable to provide dispensing devices and methods that are capable of positioning and delivering smaller amounts of liquid than conventional dispensing devices, for example on the order of a few microliters and/or a few nanoliters.
Another desirable aspect includes providing dispensing devices and methods capable of multi-plexing, i.e., handling and dispensing multiple, differing types liquids, and capable of doing so with minimal risk of cross-contamination of the differing types of liquid.
Further, it may be desirable to provide dispensing devices that are reusable for repeated handling and dispensing operations, and to provide dispensing devices and methods that are robust, reliable, and/or reduce overall costs of handling and dispensing operations.